Forming strained and relaxed silicon and silicon germanium fins on the same wafer

Abstract

Various embodiments form strained and relaxed silicon and silicon germanium fins on a semiconductor wafer. In one embodiment a semiconductor wafer is formed. The semiconductor wafer comprises a substrate, a dielectric layer, and a strained silicon germanium (SiGe) layer. At least one region of the strained SiGe layer is transformed into a relaxed SiGe region. At least one strained SiGe fin is formed from a first strained SiGe region of the strained SiGe layer. At least one relaxed SiGe fin is formed from a first portion of the relaxed SiGe region. Relaxed silicon is epitaxially grown on a second strained SiGe region of the strained SiGe layer. Strained silicon is epitaxially grown on a second portion of the relaxed SiGe region. At least one relaxed silicon fin is formed from the relaxed silicon. At least one strained silicon fin is formed from the strained silicon.

What is claimed is: 
     
       1. A semiconductor wafer comprising:
 a substrate; 
 a dielectric layer formed on the substrate; 
 a pFET region comprising
 at least one fin comprising a single layer of strained silicon germanium, and 
 at least one fin comprising a single layer of relaxed silicon germanium; and 
 
 a NFET region comprising;
 at least one fin comprising strained silicon, wherein the silicon in the single layer of strained silicon is epitaxially strained based on relaxed silicon germanium, and 
 at least one fin comprising relaxed silicon, wherein the silicon in the single layer of relaxed silicon is epitaxially relaxed based on strained silicon germanium. 
 
 
     
     
       2. The semiconductor wafer of  claim 1 , wherein each of the fins of the pFET and nFET regions is formed on the dielectric layer. 
     
     
       3. The semiconductor wafer of  claim 1 , wherein the dielectric layer is a buried oxide layer. 
     
     
       4. A non-transitory computer readable medium encoded with a program for fabricating strained and relaxed silicon and silicon germanium fins on a semiconductor wafer comprising a substrate, a dielectric layer formed on and in contact with the substrate, and a strained silicon germanium (SiGe) layer formed on and in contact with the dielectric layer, the program comprising instructions configured to perform a method comprising:
 transforming at least one region of the strained SiGe layer into at least one relaxed SiGe region, wherein the strained SiGe layer is only partially transformed into at least one relaxed SiGe region; 
 after the transforming, forming at least one strained SiGe fin from at least a first strained SiGe region of the strained SiGe layer within a pFET area of the semiconductor wafer, and at least one relaxed SiGe fin from at least a first portion of the at least one relaxed SiGe region within the pFET area; 
 after forming the at least one strained SiGe fin and the at least one relaxed SiGe fin, epitaxially growing relaxed silicon on at least a second strained SiGe region of the strained SiGe layer, and strained silicon on at least a second portion of the relaxed SiGe region; and 
 forming at least one relaxed silicon fin from the relaxed silicon within a nFET are of the semiconductor wafer, and at least one strained silicon fin from the strained silicon within the nFET area. 
 
     
     
       5. The non-transitory computer readable medium of  claim 4 , wherein the method further comprises:
 forming a plurality of mandrels, wherein at least a first mandrel is formed above the first strained SiGe region and the first portion of the at least one relaxed SiGe region, and 
 wherein at least a second mandrel is formed above the second strained SiGe region and the second portion of the at least one relaxed SiGe region. 
 
     
     
       6. The non-transitory computer readable medium of  claim 5 , wherein the method further comprises:
 depositing a spacer material over the plurality of mandrels; and 
 removing the spacer material from horizontal surfaces of the plurality of mandrels, wherein the removing forms a first sidewall spacer and at least a second sidewall spacer on each of the plurality of mandrels. 
 
     
     
       7. The non-transitory computer readable medium of  claim 6 , wherein the method further comprises:
 removing the first and second sidewall spacers from at least the second mandrel; and 
 removing at least the first mandrel after the first and second sidewall spacers have been removed from at least the second mandrel, wherein the first sidewall spacer of the first mandrel remains above a portion of the at least one relaxed SiGe region, and the second sidewall spacer of the first mandrel remains above a portion of the at least first strained SiGe region. 
 
     
     
       8. The non-transitory computer readable medium of  claim 7 , wherein forming the at least one strained SiGe fin and the at least one relaxed SiGe fin further comprises:
 etching exposed regions of the strained SiGe layer and the at last one relaxed SiGe region, wherein the etching forms the at the least one relaxed SiGe fin and the at least one strained SiGe fin. 
 
     
     
       9. The non-transitory computer readable medium of  claim 7 , wherein epitaxially growing relaxed silicon and strained silicon further comprises:
 etching exposed regions of the strained SiGe layer and the at last one relaxed SiGe region, wherein the etching forms the at least second strained SiGe region and the at least second portion of the relaxed SiGe region. 
 
     
     
       10. The non-transitory computer readable medium of  claim 4 , wherein the method further comprises:
 forming a pad layer on the SiGe layer prior to transforming the at least one region of the strained SiGe layer into the relaxed SiGe region; 
 forming a plurality of mandrels, wherein at least a first mandrel is forms on a first portion of the pad layer over the first strained SiGe region and the first portion of the at least one relaxed SiGe region, and wherein at least a second mandrel is formed on at least a second portion of the pad layer over the second strained SiGe region and the second portion of the at least one relaxed SiGe region; 
 forming a first sidewall spacer and at least a second sidewall spacer on each of the plurality of mandrels; 
 removing the first and second sidewall spacers from at least the second mandrel; and 
 removing at least the first mandrel after the first and second sidewall spacers have been removed from at least the second mandrel, wherein the first sidewall spacer of the first mandrel remains over a third portion of the pad, and the second sidewall spacer of the first mandrel remains over a fourth portion of the pad layer. 
 
     
     
       11. The non-transitory computer readable medium of  claim 10 , wherein the method further comprises:
 etching exposed portions of the pad layer, wherein the second portion of the pad layer remains under the at least second mandrel, and wherein the third portion of the pad layer remains under the first sidewall of the first mandrel and the fourth portion of the pad layer remains under the second sidewall of the first mandrel; and 
 after etching the exposed portions of the pad layer, removing the second mandrel, the first sidewall of the first mandrel, and the second sidewall of the first mandrel. 
 
     
     
       12. The non-transitory computer readable medium of  claim 11 , wherein forming the at least one strained SiGe fin and the at least one relaxed SiGe fin further comprises:
 etching exposed regions of the strained SiGe layer and the at last one relaxed SiGe region, wherein the etching forms the at the least one relaxed SiGe fin under the third portion of the pad layer and the at least one strained SiGe fin under the fourth portion of the pad layer; and 
 removing at least the third and fourth portions of the pad layer, and 
 
       wherein epitaxially growing relaxed silicon and strained silicon further comprises:
 etching exposed regions of the strained SiGe layer and the at last one relaxed SiGe region, wherein the etching forms the at least second strained SiGe region and the at least second portion of the relaxed SiGe region under the at least second portion of the pad layer; and 
 removing the at least second portion of the pad layer.